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How can I decrypt a file I encrypted in PGP with someone else's key?

Posted on 2011-02-16
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Last Modified: 2012-05-11
We encrypt a file via the command line for a 3rd party with their key.  They have been reporting that around 10% of the time they can not decrypt.  

As a result we would like to decrypt out ourselves the encrypted file before we send to them to see if the decryption process fails.  If it is good then we would send them the encrypted file.  If it fails then we would re-encrypt the file.  

On one hand it sounds logical you should be able to decrypt anything you encrypt but on the other hand it makes sense if we use someone else's key to encrypt that we can decrypt.  
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Question by:Lotus30306
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treetop3 earned 167 total points
ID: 34908675
Hi,

You must make sure you have both Private and Public keys to Decrypt

Regards,
TT
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by:abbright
abbright earned 333 total points
ID: 34908696
PGP uses asymmetric key cryptography that is you encrypt using the public key and decrypt using the corresponding private key. So you can encrypt using the file using the public key of your 3rd party but you won't be able to decrypt it as you likely don't own the private key they have. Anyway you can encrypt the file using two different public keys, so in addition to the 3rd party's public key you can encrypt the file using a public key of your own as well and try to decrypt it using your private key. If that works it is likely your 3rd party can decrypt the file as well.
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by:abbright
abbright earned 333 total points
ID: 34908794
The weay to encrypt a message for multiple recipients is to use option -r multiple times, see http://linux.die.net/man/1/gpg.
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